Pre-existing Thyroid

Thyroid disease is where the thyroid gland produces either too many hormones (hyperthyroidism) or too little (hypothyroidism). Many women become pregnant with pre-existing thyroid conditions while others may develop it during pregnancy.

The condition must be managed properly to avoid serious health consequences for both mother and baby.

Symptoms of hypothyroidism are:

  • Swelling of the hands and feet
  • Muscle aches and pains
  • Feeling tired
  • Dry skin and puffiness in the face
  • Memory loss
  • Feeling the cold more than usual
  • Constipation
  • Depression
  • Cramps

Although less common, symptoms of hyperthyroidism are:

  • Weight loss or difficulty gaining weight
  • Fatigue
  • Warm skin and feeling hot
  • Rapid heartbeat or palpitations
  • Swelling of the neck (goitre)

A simple blood test done in the first trimester of pregnancy can check the thyroid levels. Pregnancy hormones can cause thyroid hormones to be raised in early pregnancy. Treatment is not required for slight changes in thyroid hormones. Diabetes and polycystic ovarian syndrome are risk factors for hypothyroidism. In pregnancy, treatment is dependent on the severity of the disease.

Treatment for hypothyroidism is considered appropriate if the abnormality is severe or persisting. It is a simple matter of starting a daily tablet of thyroxine. Blood tests are then required every 4 weeks to adjust the dose of thyroxine. Thyroxine has been used for many decades in pregnancy and has been deemed safe to use in pregnancy.

Mild cases of hyperthyroidism are normally not treated. Severe cases however are treated with anti-thyroid drugs, one type in the first trimester and then another for the remainder of the pregnancy.

After pregnancy
The two conditions are often associated with anti-thyroid antibodies and do not resolve after pregnancy.

For those with disease prior to pregnancy, dosage of medications may change during the pregnancy but usually returns to previous dose after pregnancy.